Now, as the rapid development of civil aviation, the deficiency of Aeronautical Telecommunication Network (ATN) based on the Open System Interconnection (OSI) model, becomes more and more obvious.

The Reference Model of Open Systems Interconnection and TCP/IP Protocol System are also analyzed in this paper, which prove the feasibility of this method.

This paper presents a serial communication protocol structure based on open system interconnection reference model. The function and realization method of every layer is discussed.